Fuzzy logic system for process control in chemical mechanical polishing

Abstract

The present invention provides a versatile system for controlling chemical mechanical polishing in a semiconductor manufacturing process. The system of the present inventions utilizes an in-situ chemical mechanical polishing system, having some type of measurement or metrology function, to bulk polish a semiconductor wafer to a first target threshold. Once the first target has been reached, a fuzzy logic control function, communicatively coupled to the in-situ chemical mechanical polishing system, takes control of further polishing. Measurement data from the measurement function is processed by the fuzzy logic control function, which then adjusts additional polishing time for the polishing system to render a desired wafer topography.

1. A hardware fuzzy logic processing device implementing a fuzzy logic control function for a chemical mechanical polishing system, comprising:
 an input device for receiving input data concerning current thickness, polishing momentum or rate, and an average of at least three most current thickness measurements for a semiconductor wafer being polished; 
 a membership function for output data; 
 a rule base; and 
 a fuzzy processing function for performing an inference procedure according to the rule base and the input data and for mapping a result of the fuzzy processing function into the output data membership function to determine a time adjustment for polishing of the semiconductor wafer. 
 
     
     
       2. The hardware fuzzy logic processing device of  claim 1 , wherein the fuzzy processing function is connected to control a polishing function adapted to perform a chemical mechanical polishing process on the semiconductor wafer. 
     
     
       3. The hardware fuzzy logic processing device of  claim 1 , wherein the input device is connected to a rate monitoring system. 
     
     
       4. The hardware fuzzy logic processing device of  claim 1 , wherein the received data comprises incoming thickness data for the semiconductor wafer. 
     
     
       5. The hardware fuzzy logic processing device of  claim 1 , wherein the received data comprises data from a metrology system. 
     
     
       6. The hardware fuzzy logic processing device of  claim 1 , wherein the received data comprises data from a profilometer. 
     
     
       7. The hardware fuzzy logic processing device of  claim 1 , wherein the received data comprises data from a non-contact based metrology system. 
     
     
       8. The hardware fuzzy logic processing device of  claim 1 , wherein the received data comprises data from a laser-based metrology system. 
     
     
       9. The hardware fuzzy logic processing device of  claim 1 , wherein the fuzzy processing function comprises software operating on a host processor system. 
     
     
       10. The hardware fuzzy logic processing device of  claim 1 , wherein the fuzzy processing function comprises a specialized processor device. 
     
     
       11. The hardware fuzzy logic processing device of  claim 1 , wherein the received data comprises a first target threshold. 
     
     
       12. The hardware fuzzy logic processing device of  claim 1 , wherein the received data comprises:
 a current measurement of the semiconductor wafer; 
 a plurality of recent measurements of the semiconductor wafer; and 
 a polishing rate indicator. 
 
     
     
       13. The hardware fuzzy logic processing device of  claim 1 , wherein the received data comprises a final topography target. 
     
     
       14. A hardware fuzzy logic processing device implementing a fuzzy logic control function for a chemical mechanical polishing system, comprising:
 an input device for receiving input data concerning current thickness, polishing momentum or rate, a current measurement of the semiconductor wafer, a polishing rate indicator, and an average of at least three most current thickness measurements for a semiconductor wafer being polished; 
 a membership function for output data; 
 a rule base; and 
 a fuzzy processing function for performing an inference procedure according to the rule base and the input data and for mapping a result of the fuzzy processing function into the output data membership function to determine a time adjustment for polishing of the semiconductor wafer. 
 
     
     
       15. The hardware fuzzy logic processing device of  claim 14 , wherein the received data comprises data from a laser-based metrology system. 
     
     
       16. The hardware fuzzy logic processing device of  claim 14 , wherein the fuzzy processing function comprises software operating on a host processor system. 
     
     
       17. The hardware fuzzy logic processing device of  claim 14 , wherein the fuzzy processing function comprises a specialized processor device. 
     
     
       18. The hardware fuzzy logic processing device of  claim 14 , wherein the received data comprises a first target threshold. 
     
     
       19. The hardware fuzzy logic processing device of  claim 14 , wherein the received data comprises a final topography target. 
     
     
       20. The hardware fuzzy logic processing device of  claim 14 , wherein the received data comprises incoming thickness data for the semiconductor wafer.